1. Field of the Invention
This invention relates generally to tools used to complete subterranean wells and in particular to hydraulically actuated inflatable packers.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
Sand or silt flowing into the wellbore from unconsolidated formations can lead to an accumulation of fill within the wellbore, reduced production rates and damage to subsurface production equipment. Migrating sand has the possibility of packing off around the subsurface production equipment, or may enter the production tubing and become carried into the production equipment. Due to its highly abrasive nature, sand contained within production streams can result in the erosion of tubing, flowlines, valves and processing equipment. The problems caused by sand production can significantly increase operational and maintenance expenses and can lead to a total loss of the well. One means of controlling sand production is the placement of relatively large sand (i.e., xe2x80x9cgravelxe2x80x9d) around the exterior of a slotted, perforated, or other type liner or screen. The gravel serves as a filter to help assure that formation fines and sand do not migrate with the produced fluids into the wellbore. In a typical gravel pack completion, a screen is placed in the wellbore and positioned within the unconsolidated formation that is to be completed for production. The screen is typically connected to a tool that includes a production packer and a cross-over, and the tool is in turn connected to a work or production tubing string. The gravel is pumped in a slurry down the tubing and through the cross-over, thereby flowing into the annulus between the screen and the wellbore. The liquid forming the slurry leaks off into the formation and/or through the screen, which is sized to prevent the sand in the slurry from flowing through. As a result, the sand is deposited in the annulus around the screen where it forms a gravel pack. The screen prevents the gravel pack from entering into the production tubing. It is important to size the gravel for proper containment of the formation sand, and the screen must be designed in a manner to prevent the flow of the gravel through the screen.
A problem that is frequently encountered during a well completion is the need to seal off sections of the wellbore. These sections can include areas in which an adequate gravel pack can not be obtained, such as below the bottom of the gravel pack screens where adequate circulation is difficult to achieve. In some formations, such as across a major or minor shale section, a gravel pack completion is not desirable. Sections of the hole that are not going to be completed often need to be isolated from the sections that will be completed. If these areas that are not going to be completed were left open, the gravel which is tightly packed around the gravel pack screens after a gravel pack may be able to migrate to these void areas, thereby losing the protection provided by the gravel pack completion. Once the well is placed on production, the flow of produced fluids may accelerate the gravel migration by having a fluidizing effect on the gravel. This migration could expose the screens to direct production of formation sand and could result in equipment damage, formation collapse and even the loss of the well.
Inflatable packers that comprise an inner elastomeric bladder are well known in the industry and have been used in attempts to seal off sections of a wellbore for the reasons discussed above. The bladder defines a chamber that contains a pressurized fluid which is used to inflate the packer while an exterior elastomeric body seals against the wellbore and prohibits fluid flow past the packer when in its inflated condition. Problems with inflatable packers include the possibility of bladder rupture, incomplete inflation, long term compressibility and seal leaks, any of which can deflate the bladder and result in the loss of a seal between the packer body and the wellbore. Other factors that can affect the inflatable packer reliability include elevated temperatures, pressure differentials, hole roughness and the need for the packer to maintain the seal for an extended period of time.
There is a need for improved tools and methods to increase the reliability of inflatable packers for these applications and to address the problems referred to above.
The present invention discloses apparatus and methods for use in wellbores that comprise an inflatable element. The inflatable element is adapted for inflation by gravel, preferably by a gravel laden slurry.
One embodiment of the present invention is a well completion comprising a sand screen and a gravel inflatable element. The gravel inflatable element can be capable of movement between a deflated state and an inflated state and can be inflated by a gravel laden slurry. The gravel inflatable element can comprise a top end, a bottom end, and an interior. The gravel inflatable element may further comprise a passageway allowing communication of a gravel laden slurry between the top end of the gravel inflatable element and the interior of the gravel inflatable element. The gravel inflatable element can also comprise a passageway allowing communication of the gravel laden slurry between the bottom end of the gravel inflatable element and the interior of the gravel inflatable element. The passageway may include a check valve that restricts reverse flow. In one embodiment the well completion comprises a first sand screen and a second sand screen and the gravel inflatable element can isolate the first sand screen from the second sand screen. In another embodiment the gravel inflatable element can be placed below the sand screen and isolate the sand screen from the well below the gravel inflatable element.
Another embodiment is a well tool comprising an inflatable element and a passageway communicating between an exterior and an interior of the inflatable element. The inflatable element is adapted for inflation by gravel provided through the passageway. The passageway can comprise at least one shunt tube and also a check valve that restricts reverse flow. The well tool may also comprise a first sand screen and a second sand screen with the inflatable element isolating the first sand screen from the second sand screen. The well tool is capable of being placed below the lowermost sand screen and isolate the lowermost sand screen from the well below the inflatable element.
Yet another embodiment is an apparatus comprising a tubular body member having first and second segments, each segment having an exterior and a longitudinal bore extending therethrough. A bladder is surrounding the second segment of the tubular body, the bladder having a wall and an interior. A conduit is located adjacent to the exterior of the first segment and extends through the wall of the bladder element. The conduit allows a gravel laden slurry to enter and expand the bladder and may include a check valve that restricts reverse flow. The bladder is capable of being attached to the tubular body member and expanded in a radial direction. The bladder has an upper end and a lower end, both of which are capable of being connected to the tubular body member. The second tubular body segment can comprise an upper packer head and a lower packer head, where the bladder upper end is connected to the upper packer head and the bladder lower end is connected to the lower packer head.
The conduit may extend through the upper packer head and communicate between the exterior of the first segment of the tubular body member and the interior of the bladder. It is possible for the conduit to extend through the upper and lower packer heads and communicate between the exterior of the first and third segments of the tubular body member and the interior of the bladder. At least one aperture may be present in the second segment of the tubular body member that provide fluids communication between the longitudinal bore of the tubular body member and the interior of the bladder. The apertures allow fluid communication but restrict particulate communication. The conduit enables communication between the exterior of the first segment of the tubular body member and the interior of the bladder. In a particular embodiment the apparatus further comprises a third segment of the tubular body member wherein the conduit enables communication between the exterior of the first and third segments with the interior of the bladder. The bladder may be constructed from a material that allows the passage of fluid but restricts the passage of particulates.
Still another embodiment is a wellbore isolation tool comprising a tubular body having a longitudinal bore, an expandable bladder attached to the tubular body and a conduit providing communication between the expandable bladder and the exterior of the tubular body. The conduit allows a gravel laden slurry to enter and expand the bladder and may comprise a check valve that restricts reverse flow. The bladder can have an upper end and a lower end where both the upper end and the lower end are connected to the tubular body. The expandable bladder may enclose a portion of the tubular body comprising at least one aperture. The apertures assist the dehydration of the gravel laden slurry by allowing fluid flow from the gravel laden slurry within the expandable bladder through the apertures in the tubular body and into the longitudinal bore of the tubular body. The apertures allow fluid communication while at the same time restricting particulate communication. The conduit can also include a check valve that restricts reverse flow.
One particular embodiment of the present invention is an apparatus comprising a tubular body member having first, second and third segments. The first and third segments being on opposite ends of the second segment and each segment having an exterior and a longitudinal bore extending therethrough. A bladder surrounds the second segment of the tubular body, the bladder having a wall and an interior. A conduit is located adjacent the first and third segments and extends through the wall of the bladder. The conduit allows a gravel laden slurry to enter and expand the bladder. The conduit enables communication between the exterior of the first and third segments with the interior of the bladder and may include a check valve to restrict reverse flow. During a gravel pack completion of a wellbore the conduit allows gravel laden slurry to communicate between the exterior of the first and third segments and the interior of the bladder. The second segment of the tubular body may comprise at least one aperture that assists the dehydration of the gravel laden slurry within the bladder. The apertures allow fluid communication while restricting particulate communication. The bladder is capable of radial expansion upon being filled with gravel. The expanded bladder can form a seal between the tubular body and the wellbore wall.
Another particular embodiment of the invention is a method of sealing an annulus in a well that comprises expanding an inflatable element with a gravel laden slurry. The inflatable element comprises a passageway communicating between an exterior and an interior of the inflatable element, the passageway may include a check valve that restricts reverse flow. The inflatable element is capable of being connected to a sand screen and the inflatable element can be inflated with the gravel laden slurry during a gravel packing of the well. The gravel packing of the well comprises pumping a gravel laden slurry into the well whereby a portion of the gravel laden slurry passes through the passageway and enters the inflatable element. The gravel laden slurry then dehydrates, leaving the inflatable element in an inflated condition filled with gravel. This method can comprise more than one inflatable elements, at least one of which is inflated with a gravel laden slurry. The inflatable element is capable of being used to seal the annulus of the well and isolate a first zone from a second zone or to seal off lower depths in the well.
Yet another embodiment is a method of completing a well comprising providing a sand screen completion having at least one inflatable element therein, gravel packing at least a portion of the well with a gravel slurry, and inflating the inflatable element with the gravel slurry. The inflatable element can comprise a passageway communicating between an exterior and an interior of the inflatable element. The passageway is capable of comprising a check valve that restricts reverse flow. The inflatable element may be connected to a sand screen and the inflatable element is made so it is capable of being inflated with the gravel slurry during a gravel packing of the well. The gravel packing of the well comprises pumping the gravel slurry into the well wherein a portion of the gravel slurry passes through the passageway and enters the inflatable element. The gravel slurry then dehydrates, leaving the inflatable element in an inflated condition filled with gravel. This method can comprise more than one inflatable elements, at least one of which is inflated with a gravel slurry. The inflatable element is capable of being used to seal the annulus of the well and isolate a first zone from a second zone or to seal off lower depths in the well.
Still another embodiment is a method of completing a wellbore by providing an apparatus comprising a tubular body member, a bladder, and a conduit. The apparatus is positioned within the wellbore and a gravel laden slurry is plumped into the wellbore. At least a portion of the slurry passes through the conduit into the bladder. The bladder is capable of expanding and forming a seal between the tubular body and a wellbore wall. The tubular body can comprise at least one aperture that assists the dehydration of the gravel laden slurry within the bladder. The apertures allow fluid communication while restricting particulate communication. The gravel pack slurry within the bladder can dehydrate, leaving the bladder filled with gravel in an expanded state.
Another particular embodiment is a method of completing a wellbore by providing an apparatus comprising a tubular body member having first, second and third segments, each segment having an exterior and a longitudinal bore extending therethrough. An annular bladder surrounds the second segment of the tubular body, the bladder having a wall and an interior. A conduit is located adjacent to the exterior of the first and third segments and extends through the wall of the bladder, the conduit capable of comprising a check valve to restrict reverse flow. The apparatus is positioned within the wellbore and a gravel laden slurry is pumped into the wellbore. At least a portion of the slurry passes through the conduit into the bladder. The bladder is capable of expansion and forming a seal between the tubular body and the wellbore wall. The second segment of the tubular body can further comprise at least one aperture that assists the dehydration of the gravel laden slurry within the bladder. The apertures allow fluid communication between the interior of the bladder and the longitudinal bore of the tubular body member while restricting particulate communication. The gravel pack slurry within the bladder can dehydrate, leaving the bladder filled with gravel in an expanded state.
Yet another embodiment is a method of completing a wellbore by providing an apparatus comprising a tubular body having a longitudinal bore, an expandable bladder attached to the tubular body and a conduit providing communication between the bladder and the exterior of the tubular body. The apparatus is positioned within the wellbore and a gravel laden slurry is pumped into the wellbore. At least a portion of the slurry passes through the conduit into the bladder, the conduit capable of comprising a check valve to restrict reverse flow. The bladder can expand and form a seal between the tubular body and the wellbore wall. The tubular body may further comprise at least one aperture that assists the dehydration of the gravel laden slurry within the bladder. The apertures allow fluid communication between the interior of the bladder and the longitudinal bore of the tubular body member while restricting particulate communication. The gravel pack slurry within the bladder can dehydrate, leaving the bladder filled with gravel in an expanded state.
The present invention describes tools and methods of completing a wellbore that comprise an inflatable packer element that is adapted for inflation by gravel. This invention offers a number of benefits over conventional wellbore completion tools. One advantage is the ability to inflate the gravel inflatable element at the same time as when performing a gravel pack completion on the well, thus saving time and expense. A further benefit is the ability to utilize carrier fluids that are compatible with the well completion, thus minimizing the risk of formation damage as compared to methods of inflating an isolation packer using cement, curable resins or mud based fluid. Another benefit is that since the inflatable element is filled with a solid material instead of a liquid, a loss of hydraulic seal will not necessarily result in the deflation of the tool, thus improving the reliability of the inflatable packer.